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Vianello C, Dal Bello F, Shin SH, Schiavon S, Bean C, Magalhães Rebelo AP, Knedlík T, Esfahani EN, Costiniti V, Lacruz RS, Covello G, Munari F, Scolaro T, Viola A, Rampazzo E, Persano L, Zumerle S, Scorrano L, Gianelle A, Giacomello M. High-Throughput Microscopy Analysis of Mitochondrial Membrane Potential in 2D and 3D Models. Cells 2023; 12:cells12071089. [PMID: 37048162 PMCID: PMC10093082 DOI: 10.3390/cells12071089] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/24/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023] Open
Abstract
Recent proteomic, metabolomic, and transcriptomic studies have highlighted a connection between changes in mitochondria physiology and cellular pathophysiological mechanisms. Secondary assays to assess the function of these organelles appear fundamental to validate these -omics findings. Although mitochondrial membrane potential is widely recognized as an indicator of mitochondrial activity, high-content imaging-based approaches coupled to multiparametric to measure it have not been established yet. In this paper, we describe a methodology for the unbiased high-throughput quantification of mitochondrial membrane potential in vitro, which is suitable for 2D to 3D models. We successfully used our method to analyze mitochondrial membrane potential in monolayers of human fibroblasts, neural stem cells, spheroids, and isolated muscle fibers. Moreover, by combining automated image analysis and machine learning, we were able to discriminate melanoma cells from macrophages in co-culture and to analyze the subpopulations separately. Our data demonstrated that our method is a widely applicable strategy for large-scale profiling of mitochondrial activity.
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Affiliation(s)
- Caterina Vianello
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | - Federica Dal Bello
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | - Sang Hun Shin
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | - Sara Schiavon
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | - Camilla Bean
- Department of Medicine, University of Udine, Piazzale Kolbe, 33100 Udine, Italy
| | | | - Tomáš Knedlík
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | | | - Veronica Costiniti
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Rodrigo S. Lacruz
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Giuseppina Covello
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
| | - Fabio Munari
- Department of Biomedical Sciences, Via Ugo Bassi 58B, 35131 Padova, Italy
- Pediatric Research Institute, Città della Speranza Foundation, Corso Stati Uniti 4 F, 35127 Padova, Italy
| | - Tommaso Scolaro
- Pediatric Research Institute, Città della Speranza Foundation, Corso Stati Uniti 4 F, 35127 Padova, Italy
- Laboratory of Tumor Inflammation and Angiogenesis, Center for Cancer Biology, Department of Oncology, KU Leuven, B3000 Leuven, Belgium
| | - Antonella Viola
- Department of Biomedical Sciences, Via Ugo Bassi 58B, 35131 Padova, Italy
- Pediatric Research Institute, Città della Speranza Foundation, Corso Stati Uniti 4 F, 35127 Padova, Italy
| | - Elena Rampazzo
- Pediatric Research Institute, Città della Speranza Foundation, Corso Stati Uniti 4 F, 35127 Padova, Italy
- Oncohematology, Department of Women’s and Children’s Health, University of Padova, Via Giustiniani 3, 35128 Padova, Italy
| | - Luca Persano
- Pediatric Research Institute, Città della Speranza Foundation, Corso Stati Uniti 4 F, 35127 Padova, Italy
- Oncohematology, Department of Women’s and Children’s Health, University of Padova, Via Giustiniani 3, 35128 Padova, Italy
| | - Sara Zumerle
- Department of Medicine, University of Padova, Via Giustiniani 2, 35128 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Giuseppe Orus 2, 35128 Padova, Italy
| | - Luca Scorrano
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Giuseppe Orus 2, 35128 Padova, Italy
| | - Alessio Gianelle
- National Institute for Nuclear Physics, Padova Division, Via Marzolo 8, 35131 Padova, Italy
| | - Marta Giacomello
- Department of Biology, University of Padova, Via Ugo Bassi 58B, 35131 Padova, Italy
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Zyrianova T, Zou K, Lopez B, Liao A, Gu C, Olcese R, Schwingshackl A. Activation of Endothelial Large Conductance Potassium Channels Protects against TNF-α-Induced Inflammation. Int J Mol Sci 2023; 24:4087. [PMID: 36835507 PMCID: PMC9961193 DOI: 10.3390/ijms24044087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/30/2023] [Accepted: 02/09/2023] [Indexed: 02/22/2023] Open
Abstract
Elevated TNF-α levels in serum and broncho-alveolar lavage fluid of acute lung injury patients correlate with mortality rates. We hypothesized that pharmacological plasma membrane potential (Em) hyperpolarization protects against TNF-α-induced CCL-2 and IL-6 secretion from human pulmonary endothelial cells through inhibition of inflammatory Ca2+-dependent MAPK pathways. Since the role of Ca2+ influx in TNF-α-mediated inflammation remains poorly understood, we explored the role of L-type voltage-gated Ca2+ (CaV) channels in TNF-α-induced CCL-2 and IL-6 secretion from human pulmonary endothelial cells. The CaV channel blocker, Nifedipine, decreased both CCL-2 and IL-6 secretion, suggesting that a fraction of CaV channels is open at the significantly depolarized resting Em of human microvascular pulmonary endothelial cells (-6 ± 1.9 mV), as shown by whole-cell patch-clamp measurements. To further explore the role of CaV channels in cytokine secretion, we demonstrated that the beneficial effects of Nifedipine could also be achieved by Em hyperpolarization via the pharmacological activation of large conductance K+ (BK) channels with NS1619, which elicited a similar decrease in CCL-2 but not IL-6 secretion. Using functional gene enrichment analysis tools, we predicted and validated that known Ca2+-dependent kinases, JNK-1/2 and p38, are the most likely pathways to mediate the decrease in CCL-2 secretion.
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Affiliation(s)
- Tatiana Zyrianova
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathlyn Zou
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Benjamin Lopez
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Andy Liao
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Charles Gu
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Riccardo Olcese
- Departments of Anesthesiology and Perioperative Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Departments of Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Andreas Schwingshackl
- Departments of Pediatrics, University of California Los Angeles, Los Angeles, CA 90095, USA
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González-Sanabria N, Echeverría F, Segura I, Alvarado-Sánchez R, Latorre R. BK in Double-Membrane Organelles: A Biophysical, Pharmacological, and Functional Survey. Front Physiol 2021; 12:761474. [PMID: 34764886 PMCID: PMC8577798 DOI: 10.3389/fphys.2021.761474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/29/2021] [Indexed: 12/04/2022] Open
Abstract
In the 1970s, calcium-activated potassium currents were recorded for the first time. In 10years, this Ca2+-activated potassium channel was identified in rat skeletal muscle, chromaffin cells and characterized in skeletal muscle membranes reconstituted in lipid bilayers. This calcium- and voltage-activated potassium channel, dubbed BK for “Big K” due to its large ionic conductance between 130 and 300 pS in symmetric K+. The BK channel is a tetramer where the pore-forming α subunit contains seven transmembrane segments. It has a modular architecture containing a pore domain with a highly potassium-selective filter, a voltage-sensor domain and two intracellular Ca2+ binding sites in the C-terminus. BK is found in the plasma membrane of different cell types, the inner mitochondrial membrane (mitoBK) and the nuclear envelope’s outer membrane (nBK). Like BK channels in the plasma membrane (pmBK), the open probability of mitoBK and nBK channels are regulated by Ca2+ and voltage and modulated by auxiliary subunits. BK channels share common pharmacology to toxins such as iberiotoxin, charybdotoxin, paxilline, and agonists of the benzimidazole family. However, the precise role of mitoBK and nBK remains largely unknown. To date, mitoBK has been reported to play a role in protecting the heart from ischemic injury. At the same time, pharmacology suggests that nBK has a role in regulating nuclear Ca2+, membrane potential and expression of eNOS. Here, we will discuss at the biophysical level the properties and differences of mitoBK and nBK compared to those of pmBK and their pharmacology and function.
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Affiliation(s)
- Naileth González-Sanabria
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Felipe Echeverría
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Ignacio Segura
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Rosangelina Alvarado-Sánchez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramon Latorre
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
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TASK-1 regulates mitochondrial function under hypoxia. Biochem Biophys Res Commun 2021; 578:163-169. [PMID: 34571371 DOI: 10.1016/j.bbrc.2021.09.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 09/16/2021] [Indexed: 11/23/2022]
Abstract
TASK-1, TWIK-related acid-sensitive potassium channel 1, is a member of the two-pore- domain potassium channel family. It is constitutively active at resting potentials and strongly expressed in the heart. However, little is known about the role of TASK-1 channels in hypoxia. A cellular model of hypoxia and reoxygenation from rat heart-derived H9c2 cells or TASK-1 deficient HEK293T cells was employed to explore the role of TASK-1 channels in cytoprotection against hypoxia. The cell viability assay revealed that TASK-1 expression increased the number of viable cells subjected to 2 h of hypoxia followed by 2 h of reoxygenation (H/R). To dissect the protective role of TASK-1 on mitochondrial function, mitochondrial membrane potential (MMP) was assessed by tetramethylrhodamine fluorescence. It was demonstrated that MMP was significantly decreased by H/R, but it was maintained by TASK-1 expression or pretreatment with cyclosporin A, an inhibitor of mitochondrial permeability transition pore (mPTP). The effect of cyclosporin A on MMP was not further altered by TASK-1 expression. Moreover, TASK-1 expression significantly blocked cytochrome c release induced by H/R. While a small fraction of endogenous TASK-1 was found to colocalize with the mitochondrial marker MitoTracker in H9c2 cells, H/R did not alter the extent of colocalization of TASK-1 with MitoTracker. The total TASK-1 protein level was not significantly affected by H/R. In summary, we provided the evidence that TASK-1 channels confer cytoprotection against hypoxia-reoxygenation injury, possibly by their capacity of maintaining the mitochondrial membrane potential via inhibiting MPTP opening.
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Testai L, Sestito S, Martelli A, Gorica E, Flori L, Calderone V, Rapposelli S. Synthesis and pharmacological characterization of mitochondrial K ATP channel openers with enhanced mitochondriotropic effects. Bioorg Chem 2020; 107:104572. [PMID: 33418316 DOI: 10.1016/j.bioorg.2020.104572] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/20/2022]
Abstract
Mitochondria play a key role for deciding fate of cells and thus are considered an attractive target for pharmacological interventions focused on containment of myocardial ischemia/reperfusion (I/R) injury. Notably, the activation of mitochondrial potassium (mitoK) channels produces a mild depolarization of mitochondrial membrane, that contributes to reduce the driving force to calcium uptake and prevents the formation of mitochondrial transition membrane pore (MPTP); these events underlie anti-ischemic cardioprotection. However, an ideal mitoK channel opener should possess the fundamental requirement to be delivered at mitochondrial level; therefore, to improve the mitochondrial delivery of a previously characterized spirocyclic benzopyrane F81, new compounds have been developed. The three original triphenylphosphonium (TPP+)-derivatives of F81 (1-3), were evaluated for their cardioprotective activity on both isolated cardiac mitochondria and cardiac H9c2 cell line. Compound 1 was further investigated in an in vivo infarct model. This work confirms that the TPP+ strategy applied to mitoKATP openers could foster mitochondrial delivery and enhance the cardioprotective effects of mitochondrial activators of potassium channels.
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Affiliation(s)
- Lara Testai
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Simona Sestito
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Alma Martelli
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Era Gorica
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Lorenzo Flori
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Vincenzo Calderone
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy.
| | - Simona Rapposelli
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; CISUP, Centre for Instrumentation Sharing Pisa University, Lungarno Pacinotti 43, 56126 Pisa, Italy.
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Madreiter-Sokolowski CT, Ramadani-Muja J, Ziomek G, Burgstaller S, Bischof H, Koshenov Z, Gottschalk B, Malli R, Graier WF. Tracking intra- and inter-organelle signaling of mitochondria. FEBS J 2019; 286:4378-4401. [PMID: 31661602 PMCID: PMC6899612 DOI: 10.1111/febs.15103] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/19/2019] [Accepted: 10/22/2019] [Indexed: 12/15/2022]
Abstract
Mitochondria are as highly specialized organelles and masters of the cellular energy metabolism in a constant and dynamic interplay with their cellular environment, providing adenosine triphosphate, buffering Ca2+ and fundamentally contributing to various signaling pathways. Hence, such broad field of action within eukaryotic cells requires a high level of structural and functional adaptation. Therefore, mitochondria are constantly moving and undergoing fusion and fission processes, changing their shape and their interaction with other organelles. Moreover, mitochondrial activity gets fine-tuned by intra- and interorganelle H+ , K+ , Na+ , and Ca2+ signaling. In this review, we provide an up-to-date overview on mitochondrial strategies to adapt and respond to, as well as affect, their cellular environment. We also present cutting-edge technologies used to track and investigate subcellular signaling, essential to the understanding of various physiological and pathophysiological processes.
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Affiliation(s)
- Corina T Madreiter-Sokolowski
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria.,Department of Health Sciences and Technology, ETH Zurich, Schwerzenbach, Switzerland
| | - Jeta Ramadani-Muja
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Gabriela Ziomek
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Sandra Burgstaller
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Helmut Bischof
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Zhanat Koshenov
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Benjamin Gottschalk
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria.,BioTechMed, Graz, Austria
| | - Wolfgang F Graier
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Austria.,BioTechMed, Graz, Austria
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Chang L, Zhang X, Gong P, Wang Y, Du B, Li J. Identification and characterization of Letm1 gene in Toxoplasma gondii. Acta Biochim Biophys Sin (Shanghai) 2019; 51:78-87. [PMID: 30423025 DOI: 10.1093/abbs/gmy138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/11/2018] [Indexed: 01/22/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis. Previous studies have shown that the perturbation of mitochondrial metabolism in T. gondii results in growth deficiency in host cells and lack of virulence in animals. Members of this Letm1 protein family are inner mitochondrial membrane proteins which play a role in potassium and hydrogen ion exchange. Letm1 has not been characterized in T. gondii. In this study, a potential TgLetm1 gene (TgGT1_288400) with Letm1-like protein domain coding sequence was identified in T. gondii. Indirect immunofluorescence assays suggested that TgLetm1 localized to the mitochondria in tachyzoites, as indicated by the colocalization with mitochondrial marker Mitotracker. TgLetm1 was found in the membrane fraction by western blot analysis. To investigate the role of TgLetm1 in T. gondii, we generated a tetracycline-inducible TgLetm1-knock-down mutant. The conditional deletion of TgLetm1 resulted in mitochondrial swelling. Functional studies showed that the conditional deletion of TgLetm1 resulted in growth inhibition, deficiency in invasion and replication, and lack of virulence in mice.
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Affiliation(s)
- Le Chang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xichen Zhang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Pengtao Gong
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yuru Wang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Boya Du
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianhua Li
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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Boengler K, Bulic M, Schreckenberg R, Schlüter K, Schulz R. The gap junction modifier ZP1609 decreases cardiomyocyte hypercontracture following ischaemia/reperfusion independent from mitochondrial connexin 43. Br J Pharmacol 2017; 174:2060-2073. [PMID: 28369703 PMCID: PMC5466543 DOI: 10.1111/bph.13804] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 03/13/2017] [Accepted: 03/16/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Dysregulation of gap junction-mediated cell coupling contributes to development of arrhythmias and myocardial damage after ischaemia/reperfusion (I/R). Connexin 43 (Cx43) is present at ventricular gap junctions and also in the mitochondria of cardiomyocytes. The dipeptide (2S, 4R)-1-(2-aminoacetyl)-4-benzamidopyrrolidine-2-carboxylic acid (ZP1609) has antiarrhythmic properties and reduces infarct size when given at reperfusion. However, it is unclear, whether ZP1609 targets Cx43-containing mitochondria and affects cardiomyocyte hypercontracture following I/R. EXPERIMENTAL APPROACH We studied the effects of ZP1609 on the function of murine sub-sarcolemmal mitochondria (SSM, containing Cx43) and interfibrillar mitochondria (IFM, lacking Cx43). Murine isolated cardiomyocytes were subjected to simulated I/R without and with ZP1609 (applied during I/R or at the onset of reperfusion only), and the number of cardiomyocytes undergoing hypercontracture was quantified. Biochemical pathways targeted by ZP1609 in cardiomyocytes were analysed. KEY RESULTS ZP1609 inhibited ADP-stimulated respiration and ATP production in SSM and IFM. ROS formation and calcium retention capacities in SSM and IFM were not affected by ZP1609, whereas potassium uptake was enhanced in IFM. The number of rod-shaped cardiomyocytes was increased by ZP1609 (10 μM) when administered either during I/R or reperfusion. ZP1609 altered the phosphorylation of proteins contributing to the protection against I/R injury. CONCLUSIONS AND IMPLICATIONS ZP1609 reduced mitochondrial respiration and ATP production, but enhanced potassium uptake of IFM. Additionally, ZP1609 reduced the extent of cardiomyocytes undergoing hypercontracture following I/R. The protective effect was independent of mitochondrial Cx43, as ZP1609 exerts its effects in Cx43-containing SSM and Cx43-lacking IFM.
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Affiliation(s)
- Kerstin Boengler
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
| | - Marko Bulic
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
| | | | | | - Rainer Schulz
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
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McDougal AD, Dewey CF. Modeling oxygen requirements in ischemic cardiomyocytes. J Biol Chem 2017; 292:11760-11776. [PMID: 28487363 DOI: 10.1074/jbc.m116.751826] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 05/01/2017] [Indexed: 11/06/2022] Open
Abstract
Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell's condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ∼0.007 mm could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.
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Affiliation(s)
- Anthony D McDougal
- Departments of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - C Forbes Dewey
- Departments of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
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